<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
  
</head>
<body>
        <select id="province">
                <option value="-1">请选择</option>
            </select>
            <select id = "city"></select>
            <select id="country"></select>
            <script>
                var provinceArr = ['上海','江苏','河北'];
                var cityArr = [
                    ['上海市'],
                    ['苏州市','南京市','扬州市'],
                    ['石家庄','秦皇岛','张家口']
                ];
                var countryArr = [['黄浦区','静安区','长宁区','浦东区'],
                    [
                    ['虎丘区','吴中区','相城区','姑苏区','吴江区'],
                    ['玄武区','秦淮区','建邺区','鼓楼区','浦口区'],
                    ['将去','广陵区','江都区']
                    ],[
                    ['长安区','桥西区','新华区','精金矿区'],
                    ['海港区','上海馆区','北戴河区','抚宁区']
                    ['桥东区','桥西区','宣化区','下花园区']
                    ]
                ];
                function createOption(obj,data){
                    for(var i in data){
                        var op = new Option(data[i],i);
                        obj.options.add(op);
                    }
                }
                var province = document.getElementById('province');
                createOption(province,provinceArr);
                var city = document.getElementById('city');
                province.onchange = function(){
                    if(province.value>=0) {
                            city.onchange();

                        }else{
                            country.options.length = 0;
                        }
                    city.options.length= 0;
                    createOption(city,cityArr[province.value])
        
                };
                var countryArr = document.getElementById('country');
                province.onchange = function(){
                    city.options.length= 0;
                    createOption(country,countryArr[province.value][city.value]);};
                    province.onchange = function(){
                        city.options.length();
                        createOption(city,cityArr[province.value])
                        if(province.value>=0) {
                            city.onchange();

                        }else{
                            country.options.length = 0;
                        }
                    }
            </script>
</body>
</html>